Geology final

The United States mainland is characterized by which of the following tectonic margins:

A convergent margin with deep sea trench and volcanoes on the mainland A transform margin characterized by frequent strong earthquakes A Passive continental margin characterized by deep sedimentary deposits

Pangea is a name for

A former supercontinent that was made up of all present continents

Oceanic crust always subducts below continental crust because it is:

Composed of denser rocks

Alfred Wegener developed what concept that lead to the Theory of Plate Tectonics:

Continental Drift

Geology is different than physics or chemistry because

Geology is a diachronous science, so the geological record has been unique through time in any one location

Geology

Is a process of observing contemporary Earth materials and the rock record; creating and testing hypotheses to explain the processes that form these different rocks types; and relating these to the development of the Earth through time.

At convergent plate tectonic margins:

Plates come together and oceanic crust is recycled back into the mantle

At divergent plate boundaries:

Plates move apart and new lithosphere is created.

20th century observations (1920's to 1960's) along mid-ocean ridges went against older notions of the nature of the ocean because:

The seafloor was youngest in the middle and composed of volcanic rock The ocean was shallower in the middle than along the sides of the ocean There was almost no sediment in the middle of the ocean

Coarse-textured igneous rocks have large crystals because:

They have cooled slowly

How do geomagnetic isochrons on the ocean seafloor indicate where there is a faster rate of spreading at a mid-ocean spreading center than others:

Where isochrons are wider and farther apart